As I understand things, when the heap usage of a Region Server reachesthe hbase.regionserver.global.memstore.upperLimit (5GB in this case), allupdates are blocked and all MemStores are flushed (until lowerLimit isreached - 4.5GB in this case).

During massive writes to HBase I see some of the Region Servers constantly(not just spikes) over 7GB and spiking to 9 from time to time.

Why is That ? is there anything wrong with the configurations I used ?Is there a better way to control the Region Server memory usage ?

> During massive writes to HBase I see some of the Region Servers constantly> (not just spikes) over 7GB and spiking to 9 from time to time.>> Why is That ? is there anything wrong with the configurations I used ?> Is there a better way to control the Region Server memory usage ?>

Why are you worried about it? You have already allocated the 10G tothe RS. Like a gas, the JVM will tend to grow to occupy the allocatedspace. Also remember that CMS runs sloppy and can be slow cleaning uptrash.

High level, the heap is divided between the memstore, block cache, andmiscellaneous (handler threads, flushers and compactors, etc.).

If you need more detail, dump the heap and open in a profiler. Aprofiler that can sort by deep-sizes will help you zero in on the bigobjects and allow you walk up their allocation tree. There's only afew roots in hbase (see above for a basic list).

St.Ack

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